This is the 3D printed part for Joto robotic drawing board that allow you to use a standard EXPO dry erase maker you can find in regular store. Solve the dry ink issue using the original pen set and avoid to buy the official pen set from Joto.
Just print the part and using a short rubber band to hold the pen which will provide some tension to the pen head similar to a metal spring in the original pen set. You can change any color you want to create fun drawing.